Cheesy Mac with "Velvety" Cheese

"Velvety" Cheese

• 16 oz cheddar cheese, mild, in pieces, divided
• 8 oz water
• 6 tbsp powdered milk
• 1 packet/envelope unflavored gelatin powder (approx. ¼ oz or 7 g)

"Velvety" Cheesy Mac

• 1 oz unsalted butter
• 1 oz all-purpose flour
• 1 tsp salt
• ½ tsp onion powder
• ½ tsp mustard powder
  hoặc 1 ½ tsp Dijon mustard
• 12 oz water
• 8 oz whole milk
• 1 tbsp Worcestershire sauce
• 8 oz pasta shells, dried
• green onion, thinly sliced, to garnish
• ground black pepper, to sprinkle